Introduce a global lock for the vm subsystem (vm_mtx).

vm_mtx does not recurse and is required for most low level
vm operations.

faults can not be taken without holding Giant.

Memory subsystems can now call the base page allocators safely.

Almost all atomic ops were removed as they are covered under the
vm mutex.

Alpha and ia64 now need to catch up to i386's trap handlers.

FFS and NFS have been tested, other filesystems will need minor
changes (grabbing the vm lock when twiddling page properties).

Reviewed (partially) by: jake, jhb

1 files changed, 18 insertions, 3 deletions

diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c
index da7b9cb..2a15e9c 100644
--- a/sys/kern/imgact_elf.c
+++ b/sys/kern/imgact_elf.c
@@ -230,6 +230,7 @@ elf_load_section(struct proc *p, struct vmspace *vmspace, struct vnode *vp, vm_o
 	else
 		map_len = round_page(offset+filsz) - file_addr;
 
+	mtx_lock(&vm_mtx);
 	if (map_len != 0) {
 		vm_object_reference(object);
 		vm_map_lock(&vmspace->vm_map);
@@ -244,12 +245,15 @@ elf_load_section(struct proc *p, struct vmspace *vmspace, struct vnode *vp, vm_o
 		vm_map_unlock(&vmspace->vm_map);
 		if (rv != KERN_SUCCESS) {
 			vm_object_deallocate(object);
+			mtx_unlock(&vm_mtx);
 			return EINVAL;
 		}
 
 		/* we can stop now if we've covered it all */
-		if (memsz == filsz)
+		if (memsz == filsz) {
+			mtx_unlock(&vm_mtx);
 			return 0;
+		}
 	}
 
 
@@ -270,8 +274,10 @@ elf_load_section(struct proc *p, struct vmspace *vmspace, struct vnode *vp, vm_o
 					map_addr, map_addr + map_len,
 					VM_PROT_ALL, VM_PROT_ALL, 0);
 		vm_map_unlock(&vmspace->vm_map);
-		if (rv != KERN_SUCCESS)
+		if (rv != KERN_SUCCESS) {
+			mtx_unlock(&vm_mtx);
 			return EINVAL; 
+		}	
 	}
 
 	if (copy_len != 0) {
@@ -287,14 +293,19 @@ elf_load_section(struct proc *p, struct vmspace *vmspace, struct vnode *vp, vm_o
 				 MAP_COPY_ON_WRITE | MAP_PREFAULT_PARTIAL);
 		if (rv != KERN_SUCCESS) {
 			vm_object_deallocate(object);
+			mtx_unlock(&vm_mtx);
 			return EINVAL;
 		}
 
 		/* send the page fragment to user space */
+		mtx_unlock(&vm_mtx);
 		error = copyout((caddr_t)data_buf, (caddr_t)map_addr, copy_len);
+		mtx_lock(&vm_mtx);
 		vm_map_remove(exec_map, data_buf, data_buf + PAGE_SIZE);
-		if (error)
+		if (error) {
+			mtx_unlock(&vm_mtx);
 			return (error);
+		}
 	}
 
 	/*
@@ -303,6 +314,7 @@ elf_load_section(struct proc *p, struct vmspace *vmspace, struct vnode *vp, vm_o
 	vm_map_protect(&vmspace->vm_map, map_addr, map_addr + map_len,  prot,
 		       FALSE);
 
+	mtx_unlock(&vm_mtx);
 	return error;
 }
 
@@ -498,9 +510,11 @@ exec_elf_imgact(struct image_params *imgp)
 	if ((error = exec_extract_strings(imgp)) != 0)
 		goto fail;
 
+	mtx_lock(&vm_mtx);
 	exec_new_vmspace(imgp);
 
 	vmspace = imgp->proc->p_vmspace;
+	mtx_unlock(&vm_mtx);
 
 	for (i = 0; i < hdr->e_phnum; i++) {
 		switch(phdr[i].p_type) {
@@ -557,6 +571,7 @@ exec_elf_imgact(struct image_params *imgp)
 		}
 	}
 
+	/* XXX: lock the vm_mtx when twiddling vmspace? */
 	vmspace->vm_tsize = text_size >> PAGE_SHIFT;
 	vmspace->vm_taddr = (caddr_t)(uintptr_t)text_addr;
 	vmspace->vm_dsize = data_size >> PAGE_SHIFT;